iLiad Pressure sensitivity

[sanders]

Hello,

Is there anyone with developer access and a Wacom stylus who would be interested in testing something out for me..? The stylus included with the iLiad doesn't work as well for this test, but any Wacom stylus (e.g. the ones with the "eraser" on the back) will be fine.

My test program still has (very) rough edges, so if you're trying to break the all-time iLiad uptime record, you need not apply :-)

[Windrider]

I'd be glad to give it a try! I've got a Wacom stylus from my Toshiba Portege M400 Tablet PC. Actually, I have three of them, because I bought spares and by some miracle have managed to neither break nor lose any of my current styli. Definitely standard Wacom fare- I've used my Tablet stylus with my iLiad before.

[axel77]

Originally Posted by sanders

Hello,

Is there anyone with developer access and a Wacom stylus who would be interested in testing something out for me..? The stylus included with the iLiad doesn't work as well for this test, but any Wacom stylus (e.g. the ones with the "eraser" on the back) will be fine.

My test program still has (very) rough edges, so if you're trying to break the all-time iLiad uptime record, you need not apply :-)

Shall we sponsor a WACOM pen for you?

[sanders]

Originally Posted by axel77

Shall we sponsor a WACOM pen for you?

Haha, thanks - I have two. I only have one iLiad though, and since I can't use the stylus calibration data in my program, I wanted to get a feeling for how much inter-machine difference there is in stylus calibration.

That, and I was hoping to get a moral boost when people run the test app and discover that their iLiad is perfectly able to scribble pressure-sensitive sketches on. I'm rather stuck at the partial updates problem right now, so the project is in hibernate mode.

Anyway, you can grab the executable from http://www.curly-brace.com/drawtest.

Before running it, you should find out what the pid of the Xfbdev server is, and send it a "kill -SIGSTOP". You can then run drawtest and scribble a bit with your pen. You will notice that I have to refresh the entire screen, which I throttle to once every few seconds. Exit for now is simply by typing ^C in the (ssh) terminal you ran it from, after which you can kill -SIGCONT the Xfbdev server again to get your system back (you may
need to flip a few pages in the content lister to force screen redraws). I hope you will notice some gray levels depending on the pressure you're scribbling with.

The story behind all this:

I don't like the quality of scribbles very much. Since they're not anti-aliased, they look much more "grainy" than the iLiad is capable of displaying. I wanted to experiment a bit with anti-aliased scribbles and perhaps one day write a full-blown graphics program for the iLiad, offering basic shapes and freehand drawing.

I quickly found out I can't use the normal X interface. The current software interface to the tablet doesn't provide pressure data. That means I need to read the raw packets from /dev/ttyS0. I therefore can't use the calibration data and will need my own calibration routine (current calibration is _very_ crude). Also, the X server can't be running at the same time as my app since we would be competing for input on /dev/ttyS0.
Hence the stop/restart action (which, obviously, would eventually be included in the application itself).

Another tough problem is partial updates. The official scribble app uses a special interface for this, in which they send custom commands to the driver. I asked on the iRexnet developer forum in an IM to Matthijs whether there is documentation for this, because obviously flashing the entire screen all the time is a definite showstopper. I haven't heard
back on this yet.

[axel77]

I always wondered instead of doing full refreshes, how doing a local refresh and then extend the area over the whole screen like a waterdrop does when it falls into a water surface. This way I guess one could get immediate updates, while having a ghostfree image after the "wave" went over the whole screen.

I will try your application, but first I have to backup all my valuable data =)

I also wonder, can't we upgrade X? I mean there are so many x-extensions available on the PC... theoretically adding a pressuresensitivity extensions should be possible. Not?

[sanders]

Originally Posted by axel77

I also wonder, can't we upgrade X? I mean there are so many x-extensions available on the PC... theoretically adding a pressuresensitivity extensions should be possible. Not?

Probably. I just didn't feel like it, and I haven't got much experience programming X. In fact, I don't really understand why the iLiad uses X at all, and not a custom toolkit on top of, say, DirectFB or somesuch. Most applications are full-screen anyway. It would make the iLiad quite a bit "lighter", and it would boot a few seconds faster, too.

Of course, we would have lacked the nice ports of mrxvt etc., but perhaps it should only run optionally during "thinkering" and not during normal operation of the device.

[axel77]

Originally Posted by sanders

Probably. I just didn't feel like it, and I haven't got much experience programming X. In fact, I don't really understand why the iLiad uses X at all, and not a custom toolkit on top of, say, DirectFB or somesuch. Most applications are full-screen anyway. It would make the iLiad quite a bit "lighter", and it would boot a few seconds faster, too.

Of course, we would have lacked the nice ports of mrxvt etc., but perhaps it should only run optionally during "thinkering" and not during normal operation of the device.

I guess iRex considered X to be the fasted development way to get e.g. fonts rendering correct on the iLiad. Also most X client windows like the from me hated mrxvt (because of the wrong refreshes, I much rather to ssh), do feel as a big "contaminant" in the iLiad UI-design.

What we'd need to make porting at least as easy would be an almost libx11-compatible library, but working with a iLiad specific screen manager. I don't think anybody cares about compatibility to the X pipe/tcp protocol.

Too bad I currently really have to focus on another project

On a side note, there are more and more people also on the PC unhappy with X. I remember an interview of a wine-project leader beeing asking what can be done about perforamnce improvement of wine, he said he thinks they reached the limit what can be done, without changing the way X works. However X is still so dominant, I don't think there are real considerable alternatives for the PC:

[nekokami]

It would be great to have a real sketch application on the iLiad. I'll have to rummage around to find my Wacom pen.